dns换了再重启网络就可以联杰外网了

systemctl restart network
echo "nameserver 114.114.114.114" >> /etc/resolv.conf
破案了，
1 systemctl restart network
2 ping www.baidu.com
3 echo "nameserver 114.114.114.114" >> /etc/resolv.conf
4 systemctl restart network
5 成功